Compression low, now what?

[MadRat 88]

I just did a compression test on my 81', been throwing parts at it for weeks with no results and the same outcome... no top end. The compression is at 100psi on both sides, warm and cold. I would guess poor compression affects top end performance???

Any suggestions where to start next? links? anything would be appreciated.

 

[xjwmx]

I would wait and use the rebuild as a way to spend quality time with my bike in the dead of the Wisconsin winter I would borrow a compression tester from a parts store just to verify it. Then I would put a little bit of oil in the cyl and try again. If the compression goes up, it's rings, if not, it's valves.

 

[MadRat 88]

I just got the tester this morning, I'm gonna try the oil and see what happens. Yes, we all need QT in the winter, but I need to be riding until then... have an 80' or up motor with good compression

 

[xjwmx]

have an 80' or up motor with good compression

It might help if you say somebody stole your motor while you were parked at work.

 

[OakBehringer]

Remember, open throttle all the way when you test.

 

[MadRat 88]

Yep, I have it wide open. I put some oil in each cylindar after I warmed it up. Both sides went from 100 up to 108-110. So that's telling me it's the valves? I know I had them adjusted to specs, guess I need to check the seats or if I have a bent one?

 

[pamcopete]

Mad....,

The oil helps to seal the rings, so if the pressure goes up, it's the rings. Although that is low, the engine should still get up and go, so I would make a rebuild a winter project and enjoy the summer's riding. You can also try a product called "Restore" available at your local auto parts store to get you by for the summer. Just put an eye dropper of Restore directly into the cylinders through the spark plug hole. Don't put it in the gas or oil.

 

[MadRat 88]

I got another compression gauge to try and see if it reads different. Tried 2nd gauge and have 150 on both sides cold. So much for restore. I also went back to ohm the new coil, I have 5 on the primary and secondary doesn't move the needle. I can get 5 through the plug wires but nothing through the cap or coil... Do the resistor caps not allow it or am I nuts?

 

[pamcopete]

Mad....,

5 what? Ohms? K Ohms? What coil do you have? What plug caps do you have? 5K Ohms? Zero Ohms? What kind of meter are you using? What scale do you have it set on?

Use the lowest scale for the primary. Switch to a higher scale to read the secondary. if you have an auto ranging meter, you made a mistake when you bought it.

 

[MadRat 88]

4-5 ohms on primary, multimeter only has one setting for ohms with an adjust knob. I have an XS performance ignition new out of the box with 5ohm resistor caps, 7mm silicon wires. Plugs are new as well.

 

[pamcopete]

Mad...,

Have you gone back to your other thread you started? There are people there who are still trying to help you. You need to go back and tell them you're here. Like, you know, don't start a new thread every time your problem takes a new turn.

There is no such thing as a 5 Ohm resistor cap. if you are going to solve your problem, you need to get focused and be specific. You also need to get a better meter, like the one they have at Harbor Frieght for $2.99.

 

[xjwmx]

They don't make a non-auto-ranging digital meter that costs more than $2.99.

 

[MadRat 88]

I found and isolated the issue I have been chasing. Found bare wires inside the oil bag bouncing off the inside of it making sparks. I was actually going into the oil bag where all the wiring and reg/rec are hidden and wires starting throwing sparks when I was taking off the cover.

I apologize for not knowing Forum etiquette, I thank you all for your help! I have been getting 20 different answers from 20 different people and all solutions cost me money. I have been working on this bike since January and don't have another ride. So if you want to get mad at me for being frustrated and starting threads trying to figure this thing out so be it. I don't get offended when people assume they know who and what I am, I like don't get offended when you think I'm a 20 year old kid with no sense of respect for anyone or anything. If you need to know I'm 37, which I hear is the new 27 and I'm just trying to have fun and learn as much as I can when I can. So thanks PP, after reading your reply I learned something else...

Cheers! I'm going riding today!!!

 

[5twins]

Well, if the build quality of your oil bag and wiring is any indication of how you assembled the rest of the bike, you'll be back shortly, lol.

 

[tonyc]

The answers that you receive are only suggestions for you to check-out albeit excellent suggestions. No one can diagnose your problem accurately without seeing, hearing, and maybe riding your bike. You are the one that does these things and makes the decisions on their accuracy. It can be frustrating I know for sure. I always do the easiest and cheapest procedure first and work my way through until I solve the problem. Good luck and keep asking questions. Tony C